The present invention relates to a method for forming a glass-reacted-ceramic dielectric material and more particularly to such a method wherein cadmium from the glass reacts with the ceramic during the firing to maturity of the dielectric.
In the preparation of such low firing two phase (glass and ceramic) dielectric materials, it is conventional to pre-react the basic ceramic materials, such as barium titanate and calcium zirconate by prefiring or calcining at a high temperature, namely above 2200.degree. F., to form a solid solution thereof and thus to form a single phase ceramic such as an alkaline-earth titanate-zirconate. This single phase ceramic is then conventionally pulverized, mixed with a glass powder, usually in a suspension medium, deposited on a substrate or in a multi-layer stack and fired to maturity at a temperature less than about 2050.degree. F. Such a method is described in the patent to G. Maher U.S. Pat. No. 3,885,941 issued May 27, 1975 and assigned to the same assignee.
Although it is known to react two different alkaline-earth titanates in a glass flux at temperatures lower than 2050.degree. F., it has hitherto been believed that the above noted high temperature calcining step was necessary to achieve a solid solution of two basic but distinctly different ceramic materials such as titanates and zirconates.
It is an object of the present invention to provide a method for forming a glass-reacted-ceramic dielectric material wherein a mixture of two different basic ceramic materials and glass is fired to maturity achieving a solid solution of said ceramic materials that is intermixed with glass.
It is a further object of this invention to provide a method for forming a glass-reacted-ceramic dielectric material from at least two distinctly different ceramic materials and a glass, without calcining said distinctly different ceramic materials prior to mixing and firing to maturity with glass.
It is a further object of this invention to provide a low cost method for making a glass-reacted-ceramic dielectric material having a high dielectric constant at the Curie temperature.
It is a further object of this invention to provide a low cost method for making a glass-reacted-ceramic dielectric material having a Curie temperature of about 25.degree. C.